A Research On The Dynamic Load Characteristics Of A Large Face-shovel Hydraulic Excavator Attachment Based On The Muti-body Dynamics

At present, one of the main problems in domestic excavator industry is the lack of large hydraulic excavators, especially the lack of large-scale mining shovel hydraulic excavators. In order to improve the quality of our products, a large face-shovel hydraulic excavator with a capacity of7to50m3is being developed by a domestic company to compete with the same type of foreign brand. In this dissertation, based on the cooperative projects with the enterprise and the virtual prototyping technology, a research on the dynamic load characterizes of a large face-shovel hydraulic excavator attachment is developed, including the visualization research on the move performance of the shovel hydraulic excavator under various conditions; the visual calculation of the arm digging force within the all scope of work; the experimental design of the scope of work; the largest stick digging force; the parametric of the hydraulic system and the dynamic strength analysis of the shovel attachment, which can eventually solve the problems arising from unreliable design, such as the crack failure of excavator boom or arm, the unreasonable excavation area, body interference, digging force and low efficiency of the hydraulic system, by providing a theoretical basis and practical means on the design of large hydraulic excavator. The specific contents are as follows:Kinematic trajectory equations of the face-shovel attachment can be derived by D-H method and be used to analyze the major operating parameters and digging envelope diagram. And on this basis, the face-shovel kinematics virtual prototype model is built to undertake a visual analysis of athletic performance of the working device shovel digging, lifting and pushing, and draw the attachment digging envelope diagram. By the visual simulation analysis on the face-shovel attachment, even if there are no physical prototypes, the design can also meet the requirements of the scope of work of the face-shovel attachment, maximum digging force and so on. It is to provide a valuable reference for the enterprise design work.A stick digging force theoretical formula on a face-shovel excavator is established by using the torque balance method and the space vector method. Dynamic equations of the face-shovel attachment can be derived by Newton-Euler method. And on this basis, the mechanism-liquid coupling virtual prototype model is built in ADAMS. Through the spring force which is changed with the pressure of cylinder on the tip of the bucket, the stick force can be simulated. The simulated value of the stick force is compared with the theoretical value to verify the method. Finally the stick digging diagram is drawn under the stick digging condition.Based on ADAMS/Insight, the research of the experiment design about the working range, the maximum stick digging force and the work efficiency of the face-shovel attachment are completed. By repeated experimental simulations on the virtual prototype, the influence on the performance of the attachment are analyzed when a sets of design variables changed at the same time and the best design of the prototype performance can be chosen. By using ADAMS software, the parameters prototype model on the face-shovel attachment is established and the influence of the spatial location change about the attachment’s9key hinge points to the hydraulic face-shovel attachment working scope and the maximum stick digging force is researched. It is also studied that the influence on the flow of the pressure relief valve, tubing length, diameter and other parameters on the face-shovel attachment hydraulic system lifting time during mining and lifting process. From the results, the better design parameters are preferred. And the APH method is used to choose the better design of the hydraulic attachment which has better movement performance and digging performance.In order to simulate the dynamic performance of the face-shovel attachment more realistically and accurately during the process of the work, the attachment’s arm and boom are treated as the flexible body, and the rigid-flexible, mechanism-liquid coupling virtual prototype model is established. During digging and lifting process in high efficiency or in maximum digging force ways, the dynamic stresses of the attachment are analyzed in ADAMS. And the gravity of its components and the material in the bucket are all considered during the analysis process. The results provide a theoretical basis for a further research on the mechanical properties of the excavator attachment as well as dynamic design.In summary, the kinemics performance, the digging performance, the work efficiency, and dynamic stress about the face-shovel attachment are studied thoroughly. The experimental design of movement of the face-shovel attachment, the face-shovel digging performance and the work efficiency has been developed. The results give an effective and technical reference for the large hydraulic excavator enterprises. This study also has important practical significance to promote the scientific and technological progress of China’s excavator industry.